In general, when a vehicle travels on a curved road or a driver performs a steering operation, it may be required to estimate a radius of curvature of the moving vehicle. The estimation of the radius of curvature of the moving vehicle should be necessarily applied to realize a smart cruise control system which is a recently preferred vehicle convenience.
In the conventional technique for estimating a radius of curvature of a vehicle, a radius of curvature of a vehicle was estimated based on a yaw rate of the vehicle, a steering angle of the driver, and a velocity of the vehicle. However, because the conventional technique for estimating a radius of curvature of a vehicle is realized based on the assumption that in most cases, a change in a traveling velocity of a vehicle is not large (the vehicle moves mainly at a constant speed), accuracy of estimating the radius of curvature greatly deteriorates when the magnitude of the deceleration or acceleration of the vehicle is large. In other words, because the conventional technique for estimating a radius of curvature of a vehicle may not consider a slip occurring in a vehicle when the vehicle is accelerated or decelerated, a difference between the estimated radius of curvature of the vehicle and an actual radius of curvature of the vehicle is large.